Most Popular

You know the routine: Do a set, rest, do another set. Let's change that. "By filling your rest periods with exercises, you can improve conditioning and kickstart your metabolism," says Jim Smith, C.S.C.S., co-owner of Diesel Crew. Pick fillers that work different muscle groups than your main exercise does, and do them for 30 to 60 seconds between sets. Smith likes these pairings.